There’s really one problem at the heart of “Noah.” The film’s director doesn’t consider the source material to be sacred text, but his most invested audience does.

A lot has been made of the fact that Darren Aronofsky is a non-religious man at the helm of a biblical epic. And though the film is far from a blasphemous abomination, his lack of conviction shows.

“Noah” stays faithful to its core Genesis narrative, but everything else is fair game in Aronofsky’s cinematic sandbox. The result is an entertaining adventure that is likely to be undermined by its excess baggage.

That isn’t to say that “Noah” is a bad film. In fact, it’s pretty entertaining and it looks great. But just like with “Son of God” just a few weeks ago, any adaptation of a religious text is going to be a risky proposition. Nobody will fault you for filling in a few blanks, especially when you’re turning a few chapters of Genesis into a 140-minute film. But change too much and you run the risk of alienating your audience.

The plot of the Old Testament story has remained intact. The world has become overrun with wickedness, so God (referred throughout as “the creator”) decides to cleanse the earth in a very literal fashion. Noah (Russell Crowe) and his righteous family are called to build an ark that will preserve enough of humanity and the earth’s creatures to start over again after a massive flood wipes out everything else.

But the machinations within this plot aren’t so scripturally precise. For one thing, the core difference between Noah’s clan and the wicked masses seems to be that the good guys are hardcore vegetarian environmentalists. Giant rock monsters called “watchers” (fallen angels cursed by God for rebellion) help build the ark. And up in a nearby mountain, Noah’s grandfather Methuselah (Anthony Hopkins) is living in a cave like Ben Kenobi, pining for berries and distributing hallucinogenic tea.

Most importantly, only one of Noah’s three sons has a wife (Emma Watson), and she’s barren. This leads to a whole mess of trouble, compounded when the leader of the wicked masses, a descendant of Cain named Tubal-cain (Ray Winstone), manages to stow away on the ark.

Ultimately, “Noah” wanders a little too far from its source, especially in the film’s second half. “Son of God” certainly had its flaws, but the fact that it was made by people who believed in its subject gave it a clear ethos. In “Noah,” Aronofsky may have left God in the equation, but the director’s twisting of the narrative to suit his own purposes results in a deity whose actions are confusing at best.

Not that there isn’t a valid reason to adjust the storyline. The original Genesis tale is pretty linear and doesn’t lend itself to a lot of cinematic tension. It also doesn’t help that the audience already knows how the story ends. But in order to provide that precious tension, Aronofsky alters characters and interpretations to a point that they become distractions. Let’s just say that a lot of audiences aren’t going to like the fact that for a good portion of the film Noah is the bad guy.

Crowe does a serviceable job as Noah, though his changing hairstyles seem to telegraph as much nuance as his performance. Watson and Jennifer Connelly (who plays Noah’s wife) bring their usual presence, and Logan Lerman does a nice job as Ham (the more bitter of Noah’s bachelor sons). And even though he doesn’t have a lot to do, it’s hard to picture anyone other than Hopkins playing the world’s oldest human.

You’d have to imagine that the primary Hollywood appeal of "Noah" lays in its visual potential, and its cinematography is certainly one of the film’s stronger points. The landscapes range from gorgeous to post-apocalyptic, and all are striking. Strangely, much of the visual accomplishment takes place before the flood itself, and even the CGI animal content is quite marginal. Only a small amount of time is dedicated to the flood’s destructive mayhem, though one powerful image of victims clinging to a rock is especially memorable. There’s also plenty of violence to go around, both before and after the destruction. “Noah” manages to stay in PG-13 territory, but just barely.

The verdict is simple: If your expectations lie in chapter and verse authenticity, “Noah” will confuse and disappoint. But if you’re OK with a very liberal interpretation of the source material, “Noah” should entertain. Either way, Charleton Heston is still flying solo on the Mount Rushmore of Bible epics.

“Noah” received its PG-13 rating for intense violence and destructive mayhem, as well as some mild sexuality.

Joshua Terry is a freelance writer and photojournalist who appears weekly on "The KJZZ Movie Show" and also teaches English composition for Salt Lake Community College. You can see more of his work at woundedmosquito.com.